Beta-hydroxy-beta-methylbutyrate (HMB) is a naturally occurring amino acid metabolite that is known for use in a variety of nutritional products and supplements. HMB is commonly used in such products to help build or maintain healthy muscle in selected individuals.
HMB is a metabolite of the essential amino acid leucine and has been shown to modulate protein turnover and inhibit proteolysis. In most individuals, muscle converts approximately 5% of available leucine to HMB, thus producing about 0.2 to about 0.4 grams of HMB per day in a 70 kg male. In studies where various kinds of stress were induced in animals, HMB supplementation increased lean mass. Clinical studies also suggest that HMB has at least two functions in recovery from illness or injury including protection of lean mass from stress-related damage and enhancement of protein maintenance or synthesis. It has been suggested that HMB may also be useful for enhancing immune function, reducing the incidence or severity of allergy or asthma, reducing total serum cholesterol and low density lipoprotein cholesterol, increasing the aerobic capacity of muscle, and other uses.
Since HMB is most often administered to individuals to support the development and maintenance of muscle mass and strength, many HMB products have been formulated with additional nutrients that may also be helpful in promoting healthy muscle. Some of these HMB products contain additional nutrients such as fat, carbohydrate, protein, vitamins, minerals and so forth. Calcium HMB is a commonly used form of HMB when formulated in oral nutritional products, which products include tablets, capsules, reconstitutable powders, and nutritional liquids and emulsions. Reconstitutable powders are particularly useful in this regard because such powders are often more shelf-stable than their liquid counterparts for extended periods even when formulated with multiple ingredients such as amino acids, carbohydrates, protein, and fat. These powders, however, often give off an undesirable aroma or odor, which is especially pronounced in the headspace of packaged product immediately after opening prior to use.
There is therefore a need for nutritional powders comprising HMB that are substantially free of undesirable aromas and off odors, especially when packaged and stored for extended periods.
One technique for preparing such nutritional powders is spray drying the powder. This technique involves preparing a liquid or a slurry of the nutritional composition, and spray drying the liquid or slurry to form the nutritional powder. However, the presence of calcium HMB creates stability issues in the liquids or slurries used in the preparation of the powders. In particular, in such liquids or slurries, the calcium will disassociate from the HMB and interact with the protein present in the formulation, resulting in protein aggregation and sedimentation in the slurry. The protein aggregation and sedimentation is especially troubling for the production of a spray dried nutritional powder, as the protein aggregation and sedimentation can clog the spray drying equipment and, at the very least, require more frequent maintenance and cleaning of the equipment, which would have the effect of increasing manufacture time and costs.
Accordingly, there exists a need to minimize or reduce the stability issues that occur during the preparation of spray dried nutritional powders containing calcium HMB.